A color of light depends on a spectrum of light waves having different wavelengths present in said light. Light having only wavelengths in a band of said spectrum is perceived as a certain color, such as blue, green or red. If all wavelengths are present in the light, a perceived color of said light may be characterized by a color temperature. Light comprising a large amount of light waves with a relatively short wavelength is perceived as blue and cold light, whereas light comprising a large amount of light waves with a relatively long wavelength is perceived as red and warm light. Hereinafter, a color of light refers to any combination of visible wavelengths comprised in said light.
A person may want to adjust the color of the light emitted by a light source depending on the situation and the application. Recently lamps have been developed that may be adjusted to output light with a different color. Such lamps may be based on different technologies, for example fluorescent lamps or LED technology.
The above-mentioned known color adjustable lamps, however, are not easily installable in existing electrical installations. The known color adjustable lamps may comprise a digital interface for adjusting the color. Other known color adjustable lamps may require a lamp driving circuit, which needs additional wiring for user control. Further, common lamp bulbs are not easily replaced by such a color adjustable lamp, since they require said additional circuitry and wiring and they may have a complex user interface.